The Ferris wheel concept developed by Balzano et al.  was adopted and optimised for this study. The exposure system consisted of four "Ferris wheel" exposure units, each exposing up to 65 animals at a different SAR (high, medium, low and sham).
Each wheel consisted of two parallel, circular, stainless-steel metal plates 117 mm apart, with a conical antenna in their center and stainless-steel poles short-circuiting the cylindrical cavity at a radius of 755 mm.
The positions of the animals, restrained in plastic tubes similar to those approved and used for inhalation studies, were optimized for maximum uniformity. Missing animals were replaced by conical plastic tubes filled with 36 ml of liquid, simulating the dielectric parameters of muscle tissue.
The same signal conditions as used by Repacholi et al.  were applied but with substantially improved exposure conditions, i.e., constant age-independent and uniform exposure. The highest exposure level was selected at the thermal regulation threshold, i.e., 4 W/kg [Ebert et al., 2005].
Mess- und Berechnungsdetails
The exposure levels were controlled and monitored automatically every 10 s using two EFsensors inside each wheel. The incident field was adjusted as a function of weight to obtain an age independent dose. The dosimetry was assessed according to the methodology of Kuster et al.  and provided information about whole-body, organ and peak spatially averaged SAR as well as about uncertainty, instant and lifetime variations.
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